This invention relates to a closed circuit television communication system for the transmission and reception of original video signals over wire, and more particularly to such a system in which the sync pulses are separated from the original video signal and are pulse width modulated by an audio signal, thereby enabling the video signal to carry additional information in the closed circuit system which can be recovered on reception.
Typical closed circuit television transmission over coaxial cable or wire may have restricted signal carrying capacity. In order to send additional information, such as audio signals, between the same points as the video signals, additional transmission lines and circuits are required. Some installations within or from one building to another may not be able to accommodate additional lines or may be impractical and/or uneconomical. Accordingly, sending both video and additional audio information over the same transmission line would be highly desirable.